1911 Frame build question

I am working on my first 1911a1 build. Have a 80% frame - needs slide rails cut. Plan on doing this using my drill press w/cross wise slideing vise.

Question is this: what size keyway cutter do I use, and what is the depth.

I have the blueprints, so I think I have the answers but would like to know I am right before I ruin a good frame. Also, looks like the slide rail cut is .119 +.002; so a .120 cutter should work - a 1/8 (.125) I suspect is too big. Problem is I am having trouble finding a .120 cutter. Any help appreciated by this novice.

I'm not sure if you've seen an old thread of mine somewhere in the handgun area (my first 1911 build), but I have done a number of dremel builds since off 80% frames. Now I have tried the setup you're going to do - and unless you or someone else has posted 100% success with that method I found it to be very unstable. For one thing, unless you use a mill, the cutter should be much thinner so you can make more than one run. That allows you to correct any small errors you may make. If you get a cutter that's the exact size or close, it leaves very little room for corrections.

Along those lines I found when trying the slide vise/press method the vise/press never held the frame true for the entire cut to be made. That's why when going the "poor man's route" I've always opted to using the dremel with cutoff discs. Sure, it takes longer and you go through tons of discs but you can have very good control over the depth and overall outcome of your cuts.

It's not that the setup couldn't work - I just haven't had the chance to really refine the process. If you like the idea you can always test it out using scrap metal. That should give you a good idea. As a matter of fact, from what I recall my drill press wasn't powerful enough to run a keyway cutter through that metal (it wobbled and chattered a lot) but I did have an idea of using a cutoff disc on the drill press instead. I just haven't had the chance to try it out and the dremel works so well for me at this point.

1911a1 build

C07T,

Well you saved me a bunch of time cause meanwhile I did fool around a bit with drill press/cross slide and found all the issues you mention to be relevant - wobble, chatter, etc. - this setup just doen't seem to have precise enough control, after all it is not a precision machine setup.

I wouldn't mind at all, but I no longer have any 80% frames and haven't really had the time to do any builds for awhile. If I do get my hands on another one, I'll definitely do a step-by-step of everything...

i've tried the method using a drill press. not a good idea. get a mini mill. or do it with files and a dremel. cut first with the dremel then the files. don't use a dremel cut-off wheel on anything but carbon steel. you can clamp or tape a guide of some kind on for the initial cuts. finish with a needle file and check with calipers to make sur your straight.